[ovs-discuss] Basic Questions about Queues in OVS

Peter Nase pet.nase at googlemail.com
Fri Oct 3 12:55:10 UTC 2014

Hello all,

i have a basic question about queue(s) in ovs.

As a example my Mininet-Network consists of one switch (s1) and three 
hosts (h1, h2, h3).
The links between the hosts and the switch are configured as 10000 Mbps
and communication works fine. I started iperf in server mode on h3 and
use h1, h2 as clients at the same time. Both clients send with full
speed (2x times 10000 Mbps) to h3, but the link of h3 can only process
10000 Mbps.

For my understandig there must exist a queue that fills, because host 3
can handle only 10000 Mbps. Am i'm right?

Where is this queue exactly located?
Is there one (default) queue in the switch which holds all packets to be
forwarded or is there one queue per port?
How can i get the stats of such a queue to see if it gets filled up and
see if packets are dropped because the queue is full?

I read about QoS-Queues which i can configure per port, but what about
if i do not do this. What is the default behaviour if my two hosts h1,
h2, overloads the link of h3?

If my understanding is wrong, please correct me.
Thanks for clarifying my questions.

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